| // Copyright 2019 The Go Authors. All rights reserved. | |
| // Use of this source code is governed by a BSD-style | |
| // license that can be found in the LICENSE file. | |
| //go:build unix | |
| package ld | |
| import ( | |
| "syscall" | |
| ) | |
| // Mmap maps the output file with the given size. It unmaps the old mapping | |
| // if it is already mapped. It also flushes any in-heap data to the new | |
| // mapping. | |
| func (out *OutBuf) Mmap(filesize uint64) (err error) { | |
| oldlen := len(out.buf) | |
| if oldlen != 0 { | |
| out.munmap() | |
| } | |
| for { | |
| if err = out.fallocate(filesize); err != syscall.EINTR { | |
| break | |
| } | |
| } | |
| if err != nil { | |
| // Some file systems do not support fallocate. We ignore that error as linking | |
| // can still take place, but you might SIGBUS when you write to the mmapped | |
| // area. | |
| if err != syscall.ENOTSUP && err != syscall.EOPNOTSUPP && err != syscall.EPERM && err != errNoFallocate { | |
| return err | |
| } | |
| } | |
| err = out.f.Truncate(int64(filesize)) | |
| if err != nil { | |
| Exitf("resize output file failed: %v", err) | |
| } | |
| out.buf, err = syscall.Mmap(int(out.f.Fd()), 0, int(filesize), syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_SHARED|syscall.MAP_FILE) | |
| if err != nil { | |
| return err | |
| } | |
| // copy heap to new mapping | |
| if uint64(oldlen+len(out.heap)) > filesize { | |
| panic("mmap size too small") | |
| } | |
| copy(out.buf[oldlen:], out.heap) | |
| out.heap = out.heap[:0] | |
| return nil | |
| } | |
| func (out *OutBuf) munmap() { | |
| if out.buf == nil { | |
| return | |
| } | |
| syscall.Munmap(out.buf) | |
| out.buf = nil | |
| } | |